Combined flame arrester and vent valve



Nov. .6, 1945. J DUGGAN 2,388,395

COMBINED FLAME ARRESTER AND VENT VALVE Fiied NOV. 20, 1942 3Sheets-Sheet 1 55 /a' 2&9. 1. 36 I0 9 37 r 4/ 19 z Z; 1 v 29 27 A 3; 2;

INVENTOR. James J. Duyyan ATTORNEY.

Nov. 6, "1945. J. J, DUGGAN 2,388,395

COMBINED FLAME ARRESTER AND VENT VALVE Filed Nov. 20; 1942 5Sheets-Sheet s 9 Hll- 62 I fink 1/ w.

INVENTOR;

James J. Buy an.

ATTbRNEYs.

Patented Nov. 6, 1945 UNITED STATES PATENT OFFICE cor/rema FLAMEARRESTER AND VENT VALVE James J. Duggan, Charleston, W. Va.

Application November '20, 1942, Serial No. 466,377

11 Claims.

This invention relates to a combined flame arrester and vent valve forventing pressure vessels or systems containing ignitable fluids. Invessels containing gases and vaporizable fluids, undesirable pressuresare apt to develop therein. Consequently such vessels are provided withvalve controlled breather or vent devices to. relieve pressures inexcess of a predetermined maximum. Such devices operate satisfactorilywhen the vessel contains a non-combustible fluid; but when thefluids areignitable it is the practice to provide the vent or breather openingwith a fire stop to prevent the contents of the vessel from igniting byexternal flame sources, for example when a fire occurs exteriorly of thevessel. Such fire stops or arresters are usually composed of a screenbank which forms a multiplicityof small openings through which a flamemust find ingress into the vessel so that the flame contacts the screenin such a manner that the heat of com bustion is radiated withsufficient rapidity that the vapors on the inner side of the screencannot reach ignition temperature. Thesebanks afford relief of ordinaryworking pressures, but upon sudden rise in pressure they restrict thevents to such an extent that it is impossible to relieve the pressure intime to avoid injury of the vessel orexplosion thereof.

It is, therefore, a principal object of themesent. invention to providea flame arrester-and vent valve wherein the flame arrester bank isloosely mounted in cooperating relation with the valving element andwhich is movable from its seat to effect rapid release of excessivepressureswhen those pressures cannot be relieved through the bank withsuflicient rapidity to avoid injury of the vessel.

Itis also a further object of the invention to provide a structurewherein the flame arrester bank is completely removable by excessivepressure to give full flow capacity of the vent or breather opening inwhich the bank is mounted.

Other objects of the invention are to provide a combined flame arresterand vent valve particularly adapted for venting low pressures; to

provide a combined flame arrester and vent valve of simple, inexpensiveconstruction; and .to provide a combinedflame arrester which, in thelarger sizes, may be utilized as a manhole when the cover and fire stopunit are removed therefrom.

A sudden vacuum created in a vessel may not be relieved with .sufficientrapidity through the flame arrester since the many small passesnecessary to form an efficient fire stop may resist flow of exteriorpressure into the vessel in time to avoid injury to the vessel. It is,therefore, a further object of the invention to provide a combined flamearrester and vent valve with primary and secondary vacuum relief valves,the primary valve functioning at slight vacuum condition, to relieve thevessel through the flame arrester, and the secondary valve functioningto relieve the vessel independently of the flame arrester.

Inaccomplishing these and other objects of the invention, I haveprovided improved structure, the preferred form of which is illustratedin the accompanying drawings, wherein:

Fig. 1 is a vertical section through a combined flame arrester and ventvalve embodying the features of the present invention.

Fig. 2 is a plan view of the combined flame arrester and vent valveshowing the cover or valving element and other parts partially brokenaway to better illustrate the construction.

Fig- 3 is an elevational view of the flame arrester and vent valve.

Fig. 4 is a vertical section similar to Fig. 1 but showing the valvingelement and flame arrester bank in positions for venting excessivelyhigh pressures.

Fig. 5 is a vertical section through a modified form of the invention toafford primary and secondary vacuum relief.

Fig. 6 is a partial horizontal section on the line 6-6, Fig. 5.

Referring more in detail to the drawings:

l designates a combined flame arrester and vent valve embodying thefeatures of the present invention and which includes a body 2 having anupper cylindrical wall portion 3 and a lower cone portion 4 terminatingin a flange 5 that is suitably attached to the wall of a closed vessel6, through a suitable fitting 6, by fastening devices such as cap-screwsl. The upper part of the wall portion 3 terminates in an outwardly andupwardly flaring flange 8 which provides an internal annular beveledshoulder or seat 9 and an encircling lip forming a valve seat Ill.

The wall-portion 3 forms a compartment ll of a size to contain a firestop, such as a flame arrester bank l2, having a sufficient number ofopenings l3 so that the combined flow capacity thereof may be equal toor in excess of the normal flow capacity of the inlet opening M of thebody 2 that registers with an opening [5 of the vessel 6. Thecompartment II is also of a size relative to the flame arrester bank soas to provide an annular by-pass I6 between the circumferential wall I!of the bank and the inner face of the wall 3 for a purpose laterdescribed.

The upper portion of the body 2 is ordinarily closed by a cover or ventvalve element l8 to retain a predetermined maximum working pressure inthe vessel 6 but which is movable from covering relation to allowrelease of pressure in excess of the predetermined maximum. The cover l8preferably includes a cap-like body having a top l8 of larger diameterthan the lip ll] so that an annular depending flange H3 at the marginaledge of the top I8 is spaced a suflicientdistance from the lip ill toprovide an annular outlet passageway 20 and to accommodate a flex iblevalving ring member or annulus 2|.

In the illustrated instance the cover ispivotally connected at one sidethereof with the body 2 by a hinge 22 comprising outwardly extendingears23 and 24 on the portion 3 of the body 2 and ears Z and 26 dependingfrom the flange Is and" which are connected with the ears 23 and.

24 .bya hinge rod 21 passing through suitable openings'in the respectiveears. The opposite side? of the cover is'supported in proper relationwith the lip It: by means. of an outwardly extending: lug. 28 whichcarries. a resilient button 2I9':s'eating-!the cover, as best shown inFig. l.

The flexible valvingringi'll has its outer margina l'edge 3 0. clampedbetween a ring 3| fixed to the inner face of the flange l9 anda.removabIe-I'ring-GZ that is-securedr to the fixed ring by fasteningdevices, suchas screws 33, extending through rsuitable openings in theremovable ring, through registeringopenings in the flexible ring, and:into threaded openingsinsthe fixed ring, as shownin Fig;v 2. The. inner:marginal edge of the flexible ringrests upon the seat or lip I0 and thuscooperateswiththe cover to close the passageway 2D1from-the inner flowpassageway formed by thei-compartmentrl'l and the'lower portion of thebodya'2 so asfitos retain normal working pressures withinithe vessel 6*.The valving. ring is yieldingly retained on the seat IDJ by aring-shaped weight 34' adapted to seat upon-the ringin'outwardlyspacedrelation with the seat I 0', as shown in Fig.1, theweight being retained in guided relation with the cover I8 by anoutwardly spaced guidering 35*that is connected with the weight ring byarms 3B whicl1' engage guide ribs 31 projecting inwardly from the flangeI9. In order to:support the flexible valving ring circumferentially ofthe seat H], the clampingring 32 maybe providediwithiinwardly extendingarms 38 -carrying aasupportingring 39I spaced slightly from the-flange3U".

Theflre stop or flame arrester bank previously mentionedimay be of anystandard construction and i suspendedly supported within the compartmentI if by. means of an annular, bell-shapedflange 40 of suflicient.diameter to extend across the passageway. l6 with itsrim 4| engaging theseat 9 st) as-to-normally close the outlet end of the annular passagewayl6.

It is thus obvious that normal working pressures must pass through theopenings of the flame arrester bank so that: theyact upon the innerface'of the covertop l8. When the working pressur'e'rises above'apredetermined maximum,

as governed by the weight" of the cover; the coveris raisedtherebytoefiect' lifting of the inner marginaledge of the flexible ringfromsealing contact withthe lip" seas-to allow'd'ischarge ofthe=excessive pressure toatmosphere through the annular passageway -20.-When the pressures" increase-so rapidly thatthey-cannot be adequatelyrelieved through the openings of the flame arrester bank, the increasedpressure, acting on the under side of the flange 40 and the bottom ofthe bank, bodily lifts the flame arrester so that the pressure is passedbetween the flange 40 and its seat.

Attention is directed to the fact that the inner marginal edge of theflexible sealing ring preferably overlies the marginal edge of theflange 40 so that upward movement of the flame arrester bank, responsiveto sudden rise in pressure, causes the flange to engage the projectingportion of the ring and effect positive unseating thereof.

In order that the flame arrester bank may be unseated'ata predeterminedpressure relative to or independently of the cover, the flame arresterbank is contacted by an arm 42 projecting inwardly of the portion 4 ofthe body 2, and which has a curvedend43bearing against a button 44 onthe bottom of the bank. The arm 42 is fixed on a shaft '45 which isrotatably mounted in suitable bearingsiin an outward: extension 46 ofthe body 2: One end. of: the; shaft projectsthrough a-.stuffin'g boxi4 7on-the:=extension 46 and carries an; arms4'8rwhich. projects from theshaft in an opposite direction toithe arm 42 and carries a weightflfimovablethereomwhereby the effective leverage acting onthearrester bankmay be adjuste'dzby slidingrtheweight along. the arm 48 in themanner ofapoiseon a scale beam.

vIn'lorder toguide theiflame'arrester bank during movementthereof, the.wall of the compartment It. may be provided with a series ofinwardly-extendingguide ribs-50 which loosely engage the wall l'l of theflame arrester bank, as bestishown inlFigs; 1 and-2.

Assumingthatthecombined flame arrester and ventvalve constructed andassembled as described is'mountedon a vessel fiand that normalworkingspressures are-carried in the vessel, such pressuresaar'e 'notsufficient to'efiect unseating of the cover or-"flexible valvingring.However, should the working pressures exceed the predetermined amount,-they' act through'the openings of the flame arrester: upon the cover-18 and-effect lift-- ing-ithereof' sol-that the flexible valving ringisralsedi from the seat/'10 to'allow release of the excess-pressure.

The vent valve also *functionsin case the'pres sures .in the tank shoulddrop below a predetermined-minimum,- for example-when emptying thecontents of the'ves'sel. 'Ih'isis'eifected by atmospliericpressure-acting on the under 'sideof" the flexible ringtolift the ringfrom' contact with the seat l0 and i allow exterior air to enter thevessel the sma-lhpassages increase the velocity'ofvapors passingtherethroug'h to apoint abovethe rate offlame propagation.- other words,velocity of vapor passing through" the multiplicity'of small. openingsorthrough theb'y-pass, when the arrester bank-islifted due'tcr increasedpressure, ,is

increased to the point where the velocity of the escaping vapor isfaster than a flame can' DIODE? gate in the-directlonof'thetank;Therefore the,

amear'rester-protectsthetank fromfireihazard under ordinary operation orthe valving' elements.

of the flame arrester, and:

such conditions.

Shouldpressure in thevessel rise above the point atwhich adequate reliefcannot be effected through openings inthe fiame arrester bank, thepressure acting thereon and againsttheunder side of the supporting;flange: 4D lifts the bank-so, that thepressure is by-passed.therearound. vIf the: pressure; should continue to rise, the flamearrester bank, being completely removable, may

be blown by the pressure from the compartment,

lifting the cover, and thereby completely opening theoutletthroughthebody 2.

Attention is directed'to the fact that the larger of the devices mayserve the purpose of a manholer forthe vessels on which they may be,installed. Upon opening of the cover and removal of the fire stop unitthe passageway therethrough is sufiiciently clear of obstruction toafford access into the interior of the vessel. r

. Under some conditions a dangerously high vacuum may be caused to occurin a vessel for the reason that air cannotpass through the fire stopunit {with sufficient :velocity to; prevent high vacuurns. This isobvious since with the structure illustrated, the fire stop unit retainsits seat under Therefore the modified structure is equipped with asecondary. ,vacuumrelief which becomeseffective when theprimaryrelief,or-that effected by way of the valve 2| andpassages I3, is not adequateto protect the vessel; In this form, the body member 155 is of slightlydifferent shape between the cylindrical wall portion 56 andthe baseportion 51 that attaches to the tank or vessel to be protected than theportion 4, of the body member 2 of the first described form so as toprovide a substantiallyhorizontal ,ofiset 58 circumferentially of: theportion 51 and below the'fiame arrester bank or fire stop unit 59..Provided in this offset is a substantially annular port. 66 whichconnectsthe interior-of the vesselgwith atmosphere and through whichairmay enter, the vessel independently of the fire stop unit 59 whenadequate' relief cannotbe effected therethrough by way of the primaryinlet port 6|,under control of the primary valve 62. The valve 62,weight 63 therefor, and cover, 64 are of identically the sameconstruction and function in accordance with the corresponding parts ofthe first described form of invention. In order that the port 60 may besubstantially continuous, the upper portion of the body is connected tothe lower portion by webs 65. The secondary port i normally closed by anannular valving ring 66 also preferably formed of flexible material andhaving its inner and outer edges 61 and 68 supported on annular seats 69and 10. The valving ring is supported in valving position by a metalring H which is carried by spring arms 12, the'spring arms having outerends anchored to lugs 13 on the inner wall of the body member by screws14 and the inner ends are secured to the rings 66 and H by fasteningdevices such as bolts 15. The arms 12 are designed to retain the valvingring seated under pressure differentials which may be adequatelyrelieved by the primary valve 62 through the fire stop unit 59 but whenthe vacuum increases the arms 12 yield to unseat the valving ring 66 andprovide secondary relief independently of the passages through the firestop unit, thereby assuring safety of the tank when excessively highvacuums tend to occur.

From the foregoing it is obvious that I have provided a flame arresterand vent valve which protects a vessel or pressure system from excessiveinternal and external pressure differentials, and

What I claim and desire to secure by Letters Patent is:

, 1., A combined flame arrester andvent valve including, a body memberhaving a flow passageway, a pressure vent valve cooperating :with thebody member to close said passageway and unseatable undera'predeterminedpressure to relieve pressure through the passageway, afire stop unit loosely mounted in said passageway, a bypass connectedwith the passageway and extending around thefire stop unit, and means onthe fire stop unit normally closing said by-pass, said unit beingshiftable responsive to pressure greater than said predeterminedpressure to discharge the greater pressure through said by-pass uponopening of therelief valve.

2. A combined flame arrester and vent valve including, a body memberhaving a flow passageway and a seat encircling said passageway, apressure vent valve cooperating with the body member to close saidpassageway and adapted to open under a predetermined pressure to relievepressure through the passageway, a fire stop unit in said passageway andspaced from the body member to form a passageway therearound, and aflange encircling the fire stop unit and engaging said seat ,to closethe by-pass, said unit being shiftable by pressure in excess of thepredetermined pressure to move said flange fromseating position toby-pass said'excess pressure when the vent; valve is open.

- 3. A combined flame arrester and vent valve including, a body memberhaving a flow passageway, seats encircling said passageway, a pressurevent valve cooperating with the body member. and engaging one of saidseats to closev said passageway and adapted to open under apredetermined pressure to relieve pressure through the passagewas. a.fire stop unit in said passageway and spaced from the body member toform a passageway therearound; and a flange encircling the fire stopunit and engaging said other seat to close the by-pass, said unit beingshiftable by pressure to move said flange from seating position forbypassing said excess pressure when the vent valve is open.

4. A device of the character described including, a body member having afire stop compartment, a valve seat encircling the compartment, 2. firestop seat in said compartment, a fire stop unit in said compartmenthaving a Peripheral portion engaging said fire stop seat, a flexibleannulus having its inner marginal edge supported on the valve seat, acover for said compartment, means for securing the outer marginal edgeof said annulus with the cover around the periphery thereof, and meansmovably mounting the cover on the body member.

5. A device of the character described including, a body member having afire stop compartment, a valve seat encircling the compartment, a

whichalso protects contents of.-.the: vessel from? ing; a body member:having a fire stopcompartment, a .valve seat: encircling-thecompartment} a firestopseat, afire stop unit-lin said compart menthaving. axperipheral portion engaging said;

fire stop seat, an annulus having'itsinner mar ginal edge supportedonlthe Valve seat {r cover for said compartment, means for securing: theouter marginalaedge of 'said. annulus tothe-oover aroundthe peripherythereof; means movablysupporting theoover on the body member; andmeansiin thebody member for exertingalifting leverage on the firestopmnit.

7.1 Inra combine'dfiame arrester andvent valve, ai-body member havinglaflow passageway adaptedto be connected-atone endto avessel, a-firestop unit loosely contained in said passageway to form a by-passtherearound; means onsaid unit and-engaging the body member to normallyclose the lay-pass, a cover for saidpassageway and cooperating with-thebod member to provide a port therebetween, a-relief valvenormallyclosing said port: and yieldable to provideprimarysrelief. ofsaid vessel through the fire stop unit; said/flow passageway having asecondary relief port on the vessel side of said fire stop unit, andasecondary valvecontrolling saidsecondary relief port for relieving thevessel independently A of said 'fire 'stop unit.

8; Inacombinedfiame arrester and ventvalve, a; body member having a-flowpassageway adaptedto. be connected at oneendto avessel, a fire stop-unitloosely contained in: said passageway to form a: by-pass therearound;means-onsaid unitva'ndengagingthe bodymember to normally close. thebyr-pass, a cover for said passagewayv and cooperating with the bodymember to providena port therebetween, a relief valve normally olosingisaid port and yielda'ble toprovide'primary: relief of saidvesselthrough-the. fire stop unit,. said flow passageway having asecondary relief port on.the-vesse1 side of said fire stop unit, and asecondary valve controlling-said secondary reliefport for relieving thevesselindependently or saidfire stop unit, said-primary relief .valvebeing set to operate atalower pressure differ ential than thesecondaryrelief valve.

' is seate in'said'passageway.

assesses 10; In: a combined flame arrester and 'vent valve; abbey memberhaving a fiow'passageway;

a"- pressurevent valve cooperating with the body memberto'close saidpassageway and unseatable under a predetermined pressure to relievepressure through said passageway, a fire stop'unit'in said passagewayand smaller in diameter than said passagewayto provide a by-pass aroundsaid firestop unit; means on the fire stop unit for closing: flowthrough said by-pass, and means in-s'aid' passageway providing a supportfor said fire stop unit, said fire stop unit being movable from saidsupporting means to open said bypass-when the pressure vent valve isopened in excess of said predetermined pressure.

11; In a combined flame arrester and. vent valve, a-body member havingaflow passageway through which fiuidis adaptedto flow in eitherdirection in said passageway, a fire stopunitin said passageway, aventvalve normally closing flow through'the passageway and located on oneside ofthe fire'stop unit, cooperating means on the body member andsaidfi're stop uriit'to seat Sfiid'uhi'G-lfi' one new directionthroughthe passageway; said firestop unit being movable in the otherdirection o'f'fioW throughthe passagewayresponsive-to pressure aeting onthe fire stop unit in'excess of pressure'req'ui'red to aetuatethe ventvalve; and a secondvent'valveon the opposite side of the fire stop unitfor relieving flow through the fire stop unit when thefire stop unitJANIES J A DUGGAN;

